This invention relates generally to fatigue-resistant and damage-tolerant components and methods of producing such components.
Various metallic, ceramic, and composite components, such as gas turbine engine fan and compressor blades, are susceptible to cracking from fatigue and damage (e.g. from foreign object impacts). This damage reduces the life of the part, requiring repair or replacement.
It is known to protect components from crack propagation by inducing residual compressive stresses therein. Methods of imparting these stresses include shot peening, laser shock peening (LSP), pinch peening, and low plasticity burnishing (LPB). These methods are typically employed by applying a “patch” of residual compressive stresses over an area to be protected from crack propagation, for example a leading edge of a gas turbine engine compressor blade. However, shot peening is detrimental to the surface finish and has a lot of variation in its intensity even with industry standard control systems in place. Parts like compressor airfoils lose their efficiency with rough surface finishes produced by shot peening. Also, the residual stresses imparted by shot peening are very close to the surface of the part. Laser shock peening cans be expensive due to the required specimen preparation, equipment used, and personnel training requirements. Furthermore, both shot peening and laser shock peening can be relatively slow processes.